| Message ID | 20240315222610.6870-1-osalvador@suse.de (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v2] mm,page_owner: Fix recursion | expand |
On 3/15/24 23:26, Oscar Salvador wrote: > Prior to 217b2119b9e2 ("mm,page_owner: implement the tracking of the stacks count") > the only place where page_owner could potentially go into recursion due to > its need of allocating more memory was in save_stack(), which ends up calling > into stackdepot code with the possibility of allocating memory. > > We made sure to guard against that by signaling that the current task was > already in page_owner code, so in case a recursion attempt was made, we > could catch that and return dummy_handle. > > After above commit, a new place in page_owner code was introduced where we > could allocate memory, meaning we could go into recursion would we take that > path. > > Make sure to signal that we are in page_owner in that codepath as well. > Move the guard code into two helpers {un}set_current_in_page_owner() > and use them prior to calling in the two functions that might allocate > memory. > > Signed-off-by: Oscar Salvador <osalvador@suse.de> > Fixes: 217b2119b9e2 ("mm,page_owner: implement the tracking of the stacks count") Reviewed-by: Vlastimil Babka <vbabka@suse.cz> > --- > Changes from v1 -> v2: > Wrap {un}set_current_in_page_owner directly around kmalloc call > (Vlastimil feedback) > --- > mm/page_owner.c | 33 +++++++++++++++++++++++---------- > 1 file changed, 23 insertions(+), 10 deletions(-) > > diff --git a/mm/page_owner.c b/mm/page_owner.c > index e96dd9092658..cde1ee0f9005 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -54,6 +54,22 @@ static depot_stack_handle_t early_handle; > > static void init_early_allocated_pages(void); > > +static inline void set_current_in_page_owner(void) > +{ > + /* > + * Avoid recursion. > + * > + * We might need to allocate more memory from page_owner code, so make > + * sure to signal it in order to avoid recursion. > + */ > + current->in_page_owner = 1; > +} > + > +static inline void unset_current_in_page_owner(void) > +{ > + current->in_page_owner = 0; > +} > + > static int __init early_page_owner_param(char *buf) > { > int ret = kstrtobool(buf, &page_owner_enabled); > @@ -133,23 +149,16 @@ static noinline depot_stack_handle_t save_stack(gfp_t flags) > depot_stack_handle_t handle; > unsigned int nr_entries; > > - /* > - * Avoid recursion. > - * > - * Sometimes page metadata allocation tracking requires more > - * memory to be allocated: > - * - when new stack trace is saved to stack depot > - */ > if (current->in_page_owner) > return dummy_handle; > - current->in_page_owner = 1; > > + set_current_in_page_owner(); > nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2); > handle = stack_depot_save(entries, nr_entries, flags); > if (!handle) > handle = failure_handle; > + unset_current_in_page_owner(); > > - current->in_page_owner = 0; > return handle; > } > > @@ -164,9 +173,13 @@ static void add_stack_record_to_list(struct stack_record *stack_record, > gfp_mask &= (GFP_ATOMIC | GFP_KERNEL); > gfp_mask |= __GFP_NOWARN; > > + set_current_in_page_owner(); > stack = kmalloc(sizeof(*stack), gfp_mask); > - if (!stack) > + if (!stack) { > + unset_current_in_page_owner(); > return; > + } > + unset_current_in_page_owner(); > > stack->stack_record = stack_record; > stack->next = NULL;
diff --git a/mm/page_owner.c b/mm/page_owner.c index e96dd9092658..cde1ee0f9005 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -54,6 +54,22 @@ static depot_stack_handle_t early_handle; static void init_early_allocated_pages(void); +static inline void set_current_in_page_owner(void) +{ + /* + * Avoid recursion. + * + * We might need to allocate more memory from page_owner code, so make + * sure to signal it in order to avoid recursion. + */ + current->in_page_owner = 1; +} + +static inline void unset_current_in_page_owner(void) +{ + current->in_page_owner = 0; +} + static int __init early_page_owner_param(char *buf) { int ret = kstrtobool(buf, &page_owner_enabled); @@ -133,23 +149,16 @@ static noinline depot_stack_handle_t save_stack(gfp_t flags) depot_stack_handle_t handle; unsigned int nr_entries; - /* - * Avoid recursion. - * - * Sometimes page metadata allocation tracking requires more - * memory to be allocated: - * - when new stack trace is saved to stack depot - */ if (current->in_page_owner) return dummy_handle; - current->in_page_owner = 1; + set_current_in_page_owner(); nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 2); handle = stack_depot_save(entries, nr_entries, flags); if (!handle) handle = failure_handle; + unset_current_in_page_owner(); - current->in_page_owner = 0; return handle; } @@ -164,9 +173,13 @@ static void add_stack_record_to_list(struct stack_record *stack_record, gfp_mask &= (GFP_ATOMIC | GFP_KERNEL); gfp_mask |= __GFP_NOWARN; + set_current_in_page_owner(); stack = kmalloc(sizeof(*stack), gfp_mask); - if (!stack) + if (!stack) { + unset_current_in_page_owner(); return; + } + unset_current_in_page_owner(); stack->stack_record = stack_record; stack->next = NULL;
Prior to 217b2119b9e2 ("mm,page_owner: implement the tracking of the stacks count") the only place where page_owner could potentially go into recursion due to its need of allocating more memory was in save_stack(), which ends up calling into stackdepot code with the possibility of allocating memory. We made sure to guard against that by signaling that the current task was already in page_owner code, so in case a recursion attempt was made, we could catch that and return dummy_handle. After above commit, a new place in page_owner code was introduced where we could allocate memory, meaning we could go into recursion would we take that path. Make sure to signal that we are in page_owner in that codepath as well. Move the guard code into two helpers {un}set_current_in_page_owner() and use them prior to calling in the two functions that might allocate memory. Signed-off-by: Oscar Salvador <osalvador@suse.de> Fixes: 217b2119b9e2 ("mm,page_owner: implement the tracking of the stacks count") --- Changes from v1 -> v2: Wrap {un}set_current_in_page_owner directly around kmalloc call (Vlastimil feedback) --- mm/page_owner.c | 33 +++++++++++++++++++++++---------- 1 file changed, 23 insertions(+), 10 deletions(-)